The present invention relates to an arrangement for enhancing the cooling capacity of portable personal computers. More particularly, the invention is directed to the provision of an arrangement for increasing the cooling capacity of portable personal computers, particularly such as laptop and notebook computers wherein the computer possesses a keyboard housing having a rear edge hingedly connected with the bottom of an openable display unit or assembly, and wherein heat-generating computer electronics contained in the housing has heat removed therefrom through the intermediary of heat pipes which are hingedly connected with at least one heat dissipator located in the display assembly. In essence, the inventive concept is directed to an inexpensive construction of heat pipe hinges employed in the interconnection of the keyboard housing of the portable personal computer containing the keyboard and electronics with the display assembly, wherein the heat pipes are protected from bending stresses prior to assembling the major portions of the portable personal computer, such as the keyboard housing and the display assembly.
Commencing from the time of conception and design development of computers, and especially portable personal computers; for instance, such as laptop computers or the like, there has been encountered the aspect of thermal management as a result of heat which is generated by the processor and other electronic components of the computer. As is widely known in the computer technology, excessive amounts of heat can readily degrade the performance of computers, and additionally may cause the components of the computers to be damaged. Consequently, thermal management is frequently considered to be an extremely important aspect in the design and development of computers.
The capacity and performance of portable personal computers, such as laptop computers, notebook computers or the like, has recently been enhanced to such an extent that; for example, since the beginning of 1996, the thermal dissipation requirements of portable personal computers (PCS) have increased from about 10 watts to 25 watts and even higher values. This increase in the thermal dissipation requirements is a result of ever increasing CPU performance and additional functionality; such as DVD, modem, audio and the like, which are provided by future PCS. As elucidated in an article by Albert Yu, xe2x80x9cThe Future of Microprocessorsxe2x80x9d, IEEE Micro, December 1996, pages 46 through 53, the trend of increasing power dissipation in the form of heat for portable personal computers will continue in the foreseeable future. Thus, at the widely employed A4 form factor for a portable personal computer; in essence, a 297 by 210 mm footprint, for instance, the cooling limit for a portable PC without an active cooling device, such as a cooling fan or providing additional passive cooling capacity is currently approximately 15 to 20 watts. Although cooling capacity can be added through the installation of an active cooling device, such as a fan, this is normally not desirable inasmuch as these devices take up space, consume power and generate noise. Particularly in a portable personal computer, space and battery consumption and life is at a premium, and the generating of noise is deemed to be highly undesirable. As a result, active cooling devices have been employed as a last resort in attempts to obtain additional cooling capacity. In contrast therewith, passive cooling methods and arrangements are considered to be most desirable and efficient since they do not consume any power, generate no noise and quite often take up no additional space. Thus, providing a greater cooling capacity than the current limits in order to meet the anticipated thermal dissipation requirements of future portable personal computers, represents not only a potential competitive advantage in industry, but also provides a significant product differentiation from currently available and commercially sold portable personal computers.
In particular with regard to the power consumption of laptop computers, there has been recently a continued increase in the power of the CPU. For example, the total power of a laptop computer is normally about 10 watts, and has now increased to a range of about 30 to 40 watts or higher, whereas the CPU power has been increased from about 2 to 6 watts and, conceivably, can be as high as in the 15 watt range. Most of this power will eventually be dissipated in the form of heat to the surroundings. Consequently, being able to remove increased amounts of heat from the laptop computer becomes a critical factor in the construction and operation of such laptop computers.
Various arrangements and devices for increasing the cooling capacities of portable personal computers, particularly such as laptop or notebook computers, are presently known and widely employed in the technology.
Mok, U.S. Pat. No. 5,796,581 discloses an arrangement and method for enhancing the cooling capacity of portable personal computers wherein a double-shelled rotational heat conduction apparatus has heat pipes interconnecting a liquid-crystal display with the heat-generating electronics of a laptop computer which are located in the keyboard housing, and enabling rotation of the heat pipes through a hinged construction.
Bhatia, et al., U.S. Pat. No. 5,646,822 discloses a heat pipe exchange system which consists of two heat pipes which are brought together within a hollow sleeve filled with a thermally conductive grease. The heat exchange system does not address itself to any means of lowering the thermal resistance between the two heat pipes, which is considered to be critical in actual physical applications.
Ishida, U.S. Pat. No. 5,588,483 discloses a heat radiating apparatus for a computer possessing a heat pipe which is connected to a heat radiating plate and a heat receiving plate, and a medium for heat transfer purposes.
The heat pipe includes an internal space filled with a grease having a high thermal conductivity.
Hatada, et al., U.S. Pat. No. 5,313,362 discloses a laptop or notebook computer which incorporates radiator structure including fins for dissipating and eliminating heat generated therein through convection, and further includes the utilization of heat pipes of various configurations.
Masatake Mochizuki, et al., et al. xe2x80x9cHinged Heat Pipes for Cooling Notebook PCSxe2x80x9d, Thirteenth IEEE SEMI-THERM Symposium, pages 64-72, 1997, discusses the utilization of hinged heat pipes for cooling notebook PCS. The apparatus disclosed in this publication provides for the interconnection of two heat pipes utilizing clamps, wherein there is also employed a dry contact and clamping force in order to maintain a thermal contact which is subject to mechanical wear and environmental contamination.
Although the foregoing publications to varying degrees each concern themselves with the transfer of heat from the electronics of a portable personal computer arranged in a body or housing having a keyboard therein, and wherein the heat pipes extend so as to form hinged connections oriented towards a heat sink contained in a display assembly having a display panel therein, and which is hinged to the housing, none of the publications are directed to the aspect of inexpensively manufacturing heat pipe hinges. In such constructions, a first heat pipe transfers the heat output from the first heat pipe to a second heat pipe structure which is rotationally connected to the first heat pipe to form a hinge joint, and then transferring the heat output of the second pipe to a heat spreader in the display assembly which, in turn, dissipates the heat to the surroundings. The inexpensive manufacture of such heat pipe hinges and improvements effected thereto are adapted to facilitate the assembly and repair of the computer by protecting the heat pipe components from bending stresses which are encountered prior to the major elements of the computer being assembled, or during disassembly for repair, and enabling the display assembly to be completely assembled prior to hinged attachment to the body or housing of the computer containing the keyboard and the heat-generating electronics.
In essence, an aspect which has generally not been fully addressed in the manufacture of portable personal computers resides in the fact that the display assembly which normally contains the liquid-crystal display and which constitutes the cover structure of the portable personal computer hingedly connected to the keyboard housing is generally assembled by a display vendor or in the facility of the primary manufacturer, at a location which is different from that in which the main assembly, constituting the body or housing of the portable personal computer including the keyboard electronics, is implemented. Generally the complete display assembly consists of a flat panel display, mechanical hinges, one or more circuit boards, one or more cables, a back cover and a front bezel. Normally, the entire display assembly is attached to the main body of the computer by means of protruding mechanical hinges and then the protruding cables are plugged in to form an operative circuit. Any further elements which are added to this particular assembly procedure do not lend themselves itself to this manufacturing scenario, and thereby render the assembly more costly which, in turn, increases the cost of the computer. Thus, in the event that an attachment must be made below the bezel, the latter either must be removed from the display assembly and then reattached, or the display assembly must be forwarded to a final assembly area with the bezel unattached and in a separate condition. A further instance of added manufacturing costs for implementing a final assembly procedure resides in that, if a delicate part of the display assembly is in a protruding condition, the part must be protected or risk of being broken or deformed. This, in particular, is the instance with heat pipe hinges as presently known from the prior art and employed in the technology, wherein the heat pipe hinges are either attached at an end which is located within the display assembly, or at other opposite end, which forces the heat pipe hinge to protrude from the display assembly, with the easily bendable ordinarily copper tubing of the heat pipe being exposed and resultingly unprotected. This renders the heat pipes highly susceptible to being damaged, and thereby carries the risk of destroying the integrity of the heat-removing aspects of the heat pipe arrangement.
Another problem which is encountered in the formation of such heat pipe hinges resides in that, such heat pipe hinges are frequently machined from bar stock, which renders the foregoing procedure relatively expensive in the manufacture of personal portable computers which incorporate heat pipe hinges.
Accordingly, in order to facilitate the manufacture of inexpensive heat pipe hinges for portable personal computers which meet the thermal management requirements, the invention is directed to the provision of an inexpensive mode of transferring heat through rotatably joined heat pipes from the heat generating device, such as the electronics or a processor (CPU) which is located beneath the keyboard in the base or housing of a portable personal computer to the area between a display assembly hinged to the base by means of hinged heat pipes, and wherein a large generally vertical surface is available on the display assembly for the dissipation of heat into the surroundings.
Accordingly, a primary object of the present invention resides in the provision of an arrangement and of a method for the producing of heat pipe hinges utilizing inexpensive manufacturing methods, such as through the folding or bending of sheet material or by employing inexpensive extrusions.
In that instance, the manufacturing problems encountered in the assembly of personal portable computers utilizing heat pipe hinges is addressed through manufacturing modes which absorb bending stresses which are generated in the heat pipes prior to the assembly of the computer, thereby permitting the display assembly, to be fully assembled prior to the attaching of the display assembly to the computer body or housing containing the electronics and keyboard.
In order to achieve the foregoing, pursuant to an object of the invention, the heat pipe hinges may be formed of bendable sheet metal; preferably of aluminum or copper, or through extrusions of such materials, or from highly heat-conductive materials; for example, such as a graphite fiber composite, although other materials having similar heat-conductive properties may be readily employed in connection with the present invention.